This invention relates to an interchangeable sole system for an item of footwear (e.g., shoes, boots, sandals, slippers) including a sole that can be quickly and easily replaced with other soles having different types of traction surfaces. In particular, the system includes a removable sole unit that interacts directly with a midsole of the footwear. The midsole includes receptacles adapted to help secure the sole unit to the midsole. The interchangeable sole system allows customization of an item of footwear with respect to traction, cushioning, support, fit, performance and/or aesthetic appearance.
Shoes having replaceable soles are well known and are used in many different applications. Examples of shoes where it is desired to have multiple different traction surfaces available on a single shoe are described in U.S. Pat. Nos. 6,813,847, 7,331,123, 7,520,069, and 7,984,569, the contents of which are hereby incorporated by reference in their entireties. These shoes typically include a cavity in the sole of the boot and have a sole plate fill this cavity. The cavity is typically formed in an outsole frame that attaches to a midsole. These soles also have complementary pairs of engageable elements, associated with the sole and sole plate, to provide an interference fit that helps secure the sole plate to the sole. These shoes, however, have a distinct outsole frame that guides and holds the sole plate and that is attached to the midsole.
An example of a removable sole member for a sandal is described in U.S. Pat. No. 6,442,869. The removable soles are attached to the underside of the upper sole by fasteners, screws, snaps, etc. Another example of interchangeable sole system is described in US 2003/0200675. This system includes a series of core modules, a top foot attaching member, and a bottom sole member. The top and foot members have mating components to interconnect with the core modules.
Shoes with interchangeable sole systems are typically heavier than a conventional shoe and have a bulky look. Accordingly, there is a need for a lighter and aesthetically pleasing sole system with improved performance in a variety of footwear applications.